Thursday, 8 August 2013

Ground-breaking solar energy system (?)

What do we know about solar energy? What do you think of? 

PV (photovoltaic) panels that produce electricity come to mind, or solar thermal  systems that give bath-loads of hot water for anyone who has installed them.

Then there's concentrated solar power, of which there's a nice photo and description from wikipedia here. Basically these are huge rows of curved (parabolic) mirrors that reflect sunlight to a static tank of water or oil throughout the day.  The heat generated creates steam to drive a turbine to make electricity.  

I thought that was as far as we had gone with solar systems, until I came across this radically different concept they call the Sun-Pulse.  Invented by the German physicist and inventor, Jurgen Kleinwachter, it has been built and tested in Tamera since 2008.  So, here's how it works: 

- solar energy in the form of sunlight is collected in pipes erected on a structure (in their case a greenhouse but it could be flat panels on a roof, or a series of parabolic mirrors beaming the light at a centralised tank, just like in the concentrated solar power system);

- vegetable oil is the selected medium to be heated because it has a boiling point far higher than water, so it can be heated to over 150 degrees C or higher (can't remember exactly, doesn't matter right now).  

- the veg oil is allowed to circulate around a Stirling Engine.  OK this in itself is a wonderful invention and concept all by itself - invented in 1813 by a Scotsman!  Basically it's an engine that runs on the temperature difference between two points.  There are two pistons that are driven up and down as gas is expanded when heat is applied to the "hot end" of the engine. Cold water is pumped to the cold end to maintain the temperature difference.  The pistons move and drive a flywheel, which can be connected to a generator to make electricity, or a pump to move water, or a tank to hold compressed air, and so on.  Again wikipedia has the basics here

Now, the beauty of this system we visited in Tamera was its simplicity despite the complex design and mechanics.  We were shown around by Douglas Baillie and Janos Valder, both seriously competent scientist-technicians in their own right. Douglas comes with a PHD in physics from Heriot Watt University in Scotland, which speaks for itself. 

Douglas beside the stirling engine. The insulated pipes carry the hot oil to and from the stirling engine. The
circular fly wheel on the right is rotated as the engine runs. 
 Douglas explained that all this was built on a fairly low budget, using recycled metal and basic membranes.  

Nikita, right, researching for his essay...

Inside the greenhouse Douglas explains how the "Fresnel" mirrors direct sunlight to the copper
pipes that carry the oil. 

The stirling engine here powers a 2.5KW electrical generator, but the system can do so much more, including: 

-  circulation of hot oil to a kitchen area to cook food
-  compress air for running tools
-  mechanical energy to run rotational tools or for milling, etc. 

Here's a video that explains the whole set up in 9 minutes

Later I was in touch with Jurgen (the inventor) who has started to work with a company in Germany to produce smaller, more efficient system. Jurgen explained that they have started to use the pumping capacity to capture air, remove the nitrogen to create oxygen in tanks which can then be used for welding. He is also confident that the heat can be used to run heat pumps that could run fridges. Imagine the possibilities: the capacity to create cooling in hot climates. Ice for cold stores, vaccination programmes, storing food and so on. 

Solar water pumping, Stirling-style

Next we were introduced to the Sun-Pulse Water. This is based on a similar principle: solar heat is collected in a basic dish (see photo) which runs a stirling engine, itself connected directly to a water pump.  

The team say the calculated pumping capacity for this puppy is a whopping 400,000 litres per day at negligible head, up to 80,000 litres / day from 10m depth and 15,000 l/day from 50m - in a site that has around 2,000 sunshine hours per year (in other words, forget most of the UK).

This is serious stuff. In Pakistan last year there were lakes of standing water for 7 months after a flood, inundating a massive area, as far as my eye could see in some places.  Diesel driven dewatering pumps were used but local authorities quickly ran out of money for fuel so the impact was limited.  Could this thing really move that much water in a day? (4m litres in ten days of sunshine). If so, bring-it-on...

Janos, standing beside the Sun-Pulse Water engine / pump - built with a few spare parts
bits of motorbike, some old metal and sticky back reflective foil. 

Economic analysis and comparison

The question now is to compare the costs of construction and operation against other solar or renewable energy systems.  Take your average rural village in Pakistan where the electricity supply is utterly unreliable: on average, people receive only around 4 to 6 hours per day - for which they pay around $7 per month per family.  In a village of 100 households that's around $40,000 spent over five years.  With rampant inflation that's likely to be closer to $60,000 in five years.  And remember, that's for just a few hours of power per day.  

In most villages people use this power for a bit of light, charging mobile phones and fans for the extreme heat (well over 45 degrees C for about half the year). 

So, let's assume that the community decides to apply for a micro-finance loan to erect an alternative power supply.  Their options are limited to solar PV, which would be quite expensive, and would be limited to the provision of electricity (12v or 240v if an expensive and energy-hungry inverter were bought). 

If a sun-pulse were installed, it could, potentially, provide adequate electrical power but also mechanical energy for pumping water, driving machines to allow for a vast range of micro livelihoods and, as discussed, cooling for food processing, storage etc.

That's in theory.  Now we need to put it into practice.  Our plan is to write a research proposal whereby Jurgen, Tamera and a local NGO in Pakistan would team up with a local university and a local community to build a test system. 

Funding is going to be needed to kick-start this whole process.  Training in system construction and design could take place in Tamera and later in-country, technical support and guidance from Jurgen and his colleagues in Germany and implementation, testing and research carried out in the community in Pakistan.  
The question of capital investment is really critical for this or any other energy project. I've been inspired by the work of the Grameen Bank in Bangladesh which pioneered a system of providing loans to landless poor in that country.  Then they stared Grameen Shakti, which is promoting solar PV energy systems to rural poor on a credit basis, with massive ambition to reach 15 million people by 2015.  Surely something like this could work in Pakistan and other countries to allow poor communities to access the money they are going to pay anyway over the coming years for electricity and other energy services.  

So that's the idea.  Now we have to see if it's feasible - and to find out if the Sun-Pulse offers better economics that solar photovoltaic power for people out there struggling with serious energy insecurity.